Treatment of synthetic gasoline



Oct# 21, 1952 H. w. FLEMING ETAL 2,515,036

TREATMENT oF SYNTHETIC AsoLINE Filed Feb. 16, 1948 PREHEATER I3 23SNVBIN NOIlVtIVdBS INVENTORS. H.W. FLEMING A. H. FRIEDMAN ATTORNEYSPatented Oct. 21, 1952 i TREATMENT Y SYNTHETIC GASOLINE Harold W.Fleming, Bartlesville, Okla.,'and Alvin H. Friedman, Kansas City, Mo.,assigncrs to Phillips Petroleum Company, acorporation ci Delaware,

Application February 16, 1948, Serial No. 8,674

This invention relates to 'a process for the production and treatment ofmotor fuel. In one of its more specic aspects, it relates to aprocessfor the treatment of synthetic gasoline to'improve its properties.Preferred vembodiments of the invention relate to the treatment of aFischer-Tropsch type synthetic gasoline to improve its properties.

The Fischer-Tropsch synthesis is a conversion process wherein mixturesof carbon monoxide and hydrogen are converted to hydrocarbons and lesseramounts of` oxygen-containing materials over catalysts such as iron,cobalt, and nickel. Under proper conditions and with a. suitablecatalyst, the reaction may be so controlled that the hydrocarbonsproduced are principally straight chain olens containing to l2 carbonatoms per molecule. Such yields may be obtained by using an ironcatalyst reduced from iron oxide, which contains minor quantities ofVpotassium oxide and aluminum oxide. In such a procedure, minor amountsof oxygen-containing compounds such as alcohols, aldehydes, ketones,acids, and esters are producedwCertain othese materials are benecial ascomponents of gasoline, Whereas others are detrimental. In particular,the Ci to C4 alcohols may be used to advantage in' gasolines.

Other oxygen-containing materials, particularly those of long carbonchains and boiling above 90 to 95 C., have detrimental effects iiincluded in gasoline. These oxygen-containing materials have low octaneratings, and the aldehydes are prone to decompose with resultant harmfuleliects on color, odor, and other properties of the gasoline. As anexample of rthe detrimental eiiects of these high boilingoxygen-containing materials, there is normal amyl alcohol, which has a`clear ASTM octane number of only 52.4. If these oxygen-containingmaterials are treated over catalysts which will remove organicallycombined oxygen, such as a natural clay reforming catalyst from theclass consisting of bauxite, natural clays of the bentcnitic typeincluding montmorillonite, either plain or acid treated, and brucite,bauxite being preferred, to convertv them to hydrocarbons, particularlyolenns, their octane numbers may be raised. The olefin corresponding tonormal amyl alcohol shows the improvement imparted by this treatment byhaving an octane rating of 77.1 which is 24.7 octane numbers above thatof the alcohol. In addition to converting the oxygen-containingmaterials to olens, shifting of the double bond and/or shifting of thecarbon chain of the olens 5 Claims. (Cl. M50-450)A to form more branchedchain olenns, may result with improvement in octane rating andstability. An object of this invention is to produce high quality motorfuel from hydrogen and carbon monoxide. Another object of this inventionis to provide a method for improving gasoline. Another object is toincrease the volume of gasoline range products from the Fischer-Tropschsynthesis. Another object is to improve the color and color stability ofa Fischer-Tropsch gasoline. A further object is economy in the operationof a Fischer-Tropsch process to produce gasoline. Further objects andadvantages of this invention will be apparent to one skilled in the artfrom the accompanying disclosure and discussion.

We have discovered that by separating a fraction boiling within thegasoline range from a Fischer-Tropschsynthesis and recovering a lowboiling fraction below 90 to 95 C. and a high boiling fraction above 90to 95 C., and by treating the highboiling fraction over a catalyst whichwill remove organically combined oxygen and isomerize olens, andadmixing the previously separated lowboiling fraction with the treatedhigh boiling materials, that a gasoline of improved octane rating andcolor is obtained. When a raw synthetic gasoline of the Fischer- Tropschtype is separated into fractions of gradually increasing boiling points,the color lbodies and compounds of low stability and motoriuel valuevare found primarily in the high boiling fractions, that is, above about90 to 95 C; The Cs to C7 fractions are colorless and tend to so remain,while the fractions of high molecular rWeight have excessive color andtend to darken upon standing, especially when exposed to light. Further,we have found that by operating in this manner, i. e., treating only thefraction boiling above 90` to 95 C., that a great saving in catalystconsumption is had thereby making for greater economy of operation.

In a preferred embodiment of the invention, a mixture of hydrogen andcarbon monoxide, in a'volume ratio of 2:1 is contacted with a Fischer-Tropsch type catalyst, particularly, a powdered iron catalyst made byreducing iron oxide containing 0.05 to 1.0 weight per cent potassiumoxide (KzO), and from 0.5 to 2.5 weight per cent aluminum Voxide(A1203). Suitable reaction conditions are a temperature of 290 to 350C., a pressure of to 500 pounds per square inch, and a space velocity of1000 to 4000 volumes of gas per volume of catalyst per hour. Products ofthis reaction are principally hydrocarbons along with smaller portionsof oxygen-containing materials.

The bulk of the oxygen-containing materials, however, are found in anaqueous phase.v The lower boiling of these materials, i. e., thoseboiling below about 90 to 95 C., may be recovered, if l desired, asadditional gasoline components.

A fraction of the total Fischer-Tropsch efiluent produced as describedabove, boiling in the gasoline range, such as approximately 37 to 205C., and containing both hydrocarbons and oxygencontaining materials, isrecovered for treatment in accordance with this invention. Thisparticular fraction is separated by suitable means into two portions,one boiling below 90 to 95 C. and another boiling above 90 to 95 C. Thelow boiling fraction comprises 40 to' 50 volume per cent of the totalgasoline fraction and contains hydrocarbons in the C5 to C7 range andlesser amounts of oxygen-containing materials of the C1 to C4 range. Thehigh boiling fraction, comprising 50 to 60 volume per cent of the totalgasoline fraction, is composed of Ca and heavier hydrocarbons and minorportions of C5 and heavier oxygen-containing materials. This highboiling fraction is treated over a stationary catalyst which willisomerize olerlns and remove organically combined oxygen, such asbauxite, natural clays of the bentonitic type including montmorillonite,which are plain or acid treated, and brucite, bauxite being preferred,at a temperature which is preferably in the range of 316 to 427 C., apressure of to 200 pounds per square inch, and a liquid space velocityof 1 to 10 volumes per volume of catalyst per hour. Products from thistreatment are separated, removing those materials boiling above andbelow the gasoline range. The resultant gasoline range materials arethen blended with the untreated low boiling fraction producing animproved synthetic gasoline of full boiling range, reduced oxygencontent, increased octane number, and improved color and colorstability. Furthermore, the oxygen compounds contained in this nishedproduct contribute to the high quality of the fuel.

A better understanding of our invention may be had by referring to thedrawing which is a schematic fiow diagram of a preferred embodiment.

A synthetic gasoline from a Fischer-Tropsch reaction is introducedthrough line I0 to separation means II, comprising one or morefractional distillation columns and associated equipment, where it isseparated into a low boiling fraction and a high boiling fraction. Thelow boiling fraction containing hydrocarbons and oxygen-containingcompounds is removed from separation means II through line I2 and passedto storage means 2|. The high boiling fraction is removed through lineI3 and passed through preheater I4 to contactor I5 where it is contactedwith a catalyst which will decompose oxygencontaining materials to theircorresponding olens, and which will isomerize olens. Eiiluent fromcontactor I5 is removed through line I6 and passed to separation meansII. Light materials boiling below the gasoline range are separated andremoved through line I8, and heavy materials boiling above the gasolinerange are removed through line I9. Gasoline range materials are removedthrough line and passed to storage means 2| through line I 2, where theyare admixed with the low boiling fraction removed from separation meansII through line'I2. If desired, low boiling oxygen-containing materialsin the C1 to C4 range may be separated from the aqueous phase of theFischer-Tropsch eiliuent by means not shown, and passed to storage means2l by further means not shown, where it is admixed with the othergasoline range components. Gasoline may be removed from storage means 2lthrough line 22. To regenerate the catalyst, oxygen-containingregeneration gas is introduced to contactor I5 through line 23 at anelevated temperature, and passed countercurrent to the how of materialswhich have been treated. Spent regeneration gas is removed fromcontactor I5 through line 24.

Advantages of this invention are illustrated by the following example.The reactants and their proportions, and other specific ingredients arepresented as being typical and should not be construed to limit theinvention unduly.

Example A Fischer-Tropsch synthesis gas mixture consisting of twovolumes of hydrogen and one volume of carbon monoxide is reacted over apowdered iron catalyst promoted with 0.5 weight per cent potassium oxide(KzO) and 1.5 weight per cent aluminum oxide (A1203) at a temperature of300 C., a pressure of 250 pounds per square inch gauge, and a spacevelocity of 2500 volumes of synthesis gas per volume of catalyst perhour. From a charge of 3000 cubic feet of synthesis gas 3.5 gallons ofC3 and heavier hydrocarbons are produced of which 20 volume per cent isCs and C4 hydrocarbons, 65 Volume per cent are C5 to 205 C. materials,10 per cent are materials boiling between 205 and 371 C., and 5 per centis residue boiling above 371 C. Of the gasoline range materials formed,pel` cent are unsaturated. In addition to the 3.5 gallons ofhydrocarbons formed, there are 5 gallons of aqueous layer formed. Ofthis layer, 8 volume per cent are oxygen-containing materials boilingbelow 100 C. The gasoline fraction that is recovered from the totalFischer-Tropsch product contains 10 per cent oxygen-containingmaterials.

The gasoline fraction boiling between 38 and 205 C. is separated byfractional distillation at to 95 C. into two fractions, one boilingbelow and one boiling above the 90-95 C. cut point. The high boilingfraction is treated over bauxite at a temperature of 400 C., atmosphericpressure, and a liquid space velocity of 2 volumes per volume ofcatalyst per hour, removing oxygencontaining materials and isomerizingolens. Of the fraction treated, 2 weight per cent are converted to gasesand 3 weight per cent are converted to polymers boiling above thegasoline range. The treated materials within the gasoline range arecombined with the low boiling fraction, the gasoline thus produced beingstable, free of color, and of 70 to 75 ASTM clear and 80 to 90 Researchclear octane ratings. The original untreated gasoline was unstable andhad an ASTM clear octane rating of 55 to 65.

From the foregoing disclosure, discussion, and specific example, it isseen that a Fischer- Tropsch type gasoline of high olenicity andcontaining oxygen-containing compounds is materially improved bytreatment according to this invention, thus producing a higher grademotor fuel.

Although this process has been describedr and exemplified in terms ofits preferred modifications, it is understood that Various changes maybe made without departing from the spirit and scope of the disclosureand of the claims.

We claim:

1. A process for the manufacture of an improved synthetic gasoline fromgasoline boiling range materials having a boiling point range from about37 to 205 C. produced by a Fischer- Tropsch process for the manufactureof hydrocarbons from hydrogen and carbon monoxide which comprises;separating from said materials a first fraction containing oxygenatedorganic compounds and having a boiling range above 90-95 C.; separatingfrom -said materials a second fraction containing oxygenated organiccompounds and having a boiling range below 90-95 C.; treating said rstfraction at a temperature in the range 316-427 C. with a reformingcatalyst selected from the group consisting of bauxite, brucite and anatural clay of the bentonitic type to effect the removal of thechemically combined oxygen present in said first fraction; and admixingsaid treated first fraction with said second fraction havinglits sameoriginal composition to produce an improved synthetic gasoline.

2. The process according to claim l wherein the reforming catalyst isbauxite.

3. A process for the manufacture of an improved synthetic gasoline fromgasoline boiling range materials having a boiling point range from about37 to 205 C. produced by a Fischer- Tropsch synthesis of hydrocarbonsfrom hydrogen and carbon monoxide employing an iron catalyst whichcomprises; separating from said materials a first fraction containingoxygenated organic compounds and having a boiling range above QCP-95 C.;separating from said materials a second fraction containing oxygenatedorganic compounds and having a boiling range below 90-95 C.; treatingsaid rst fraction at a temperature within the range 316-427 C., with areforming catalyst selected from a group consisting of bauxite, bruciteand a natural clay of the bentonitic type to effect the removal of thechemically combined oxygen present in said first fraction at a pressurein the range of 0-200 pounds per square inch atmospheric and a spacevelocity of l-lO liquid volume of catalyst per hour and admixing saidtreated rst fraction with said section fraction having its same,original composition to produce an improved synthetic gasoline.

4. The process according to claim 3 wherein the iron catalyst ispromoted with minor amounts of potassium oxide and aluminum oxide.

5. The process for ythe manufacture of an improved synthetic gasolinefrom gasoline boiling range materials having a boiling point range fromabout 37 to 205 C'. produced by a Fischer- Tropsch synthesis ofhydrocarbons from hydrogen and carbon monoxide over an iron ycatalystpromoted with minor amounts of potassium oxide and aluminum oxide whichcomprises; separating from said materials a first fraction containingoxygenated organic compounds and having a boiling range above -95 C.;separating from said materials a second fraction containing oxygenatedorganic compounds and having boiling range below 90-95 C., treating saidrst fraction at a temperature in the range 316- 427 C. with bauxite toeect the removal` of the chemically combined oxygen present in saidfirst fraction, at a pressure in the range 0-200 pounds per square inchatmospheric and a space velocity in the range of l-l0 liquid volume ofcatalyst per hour and admixing said treated rst fraction with saidsecond fraction having its saine` original composition to produce animproved synthetic gasoline.

HAROLD W. FLEMING.

ALVN H. FRIEDMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Germany May 1l, 1943

1. A PROCESS FOR THE MANUFACTURE OF AN IMPROVED SYNTHETIC GASOLINE FROMGASOLINE BOILING RANGE MATERIALS HAVING A BOILING POINT RANGE FROM ABOUT37* TO 205* C. PRODUCED BY A FISCHERTROPSCH PROCESS FOR THE MANUFACTUREOF HYDROCARBONS FROM HYDROGEN AND CARBON MONOXIDE WHICH COMPRISES;SEPARATING FROM SAID MATERIALS A FIRST FRACTION CONTAINING OXYGENATEDORGANIC COMPOUNDS AND HAVING A BOILING RANGE ABOVE 90*-95* C.;SEPARATING FROM SAID MATERIALS A SECOND FRACTION CONTAINING OXYGENATEDORGANIC COMPOUNDS AND HAVING A BOILING RANGE BELOW 90*-95* C.; TREATINGSAID FIRST FRACTION AT A TEMPERATURE IN THE RANGE 316*-427* C. WITH AREFORMING CATALYST SELECTED FROM THE GROUP CONSISTING OF BAUXITE,BRUCITE AND A NATURAL CLAY OF THE BENTONITIC TYPE TO EFFECT THE REMOVALOF THE CHEMICALLY COMBINED OXYGEN PRESENT IN SAID FIRST FRACTION; ANDADMIXING SAID TREATED FIRST FRACTION WITH SAID SECOND FRACTION HAVINGITS SAME ORIGINAL COMPOSITION TO PRODUCE AN IMPROVED SYNTHETIC GASOLINE.